#include <iostream>
#include <unordered_map>

using namespace std;

struct Student {
    string name;
    int age;
    string major;

    Student(string n, int a, string m) : name(n), age(a), major(m) {}
};

int main() {
    unordered_map<string, int> majorCount; 

    Student s1("张三", 20, "计算机科学");
    Student s2("李四", 19, "计算机科学");
    Student s3("王五", 21, "工业设计");
    Student s4("赵六", 20, "工业设计");
    Student s5("钱七", 18, "电子工程");

    majorCount[s1.major]++;
    majorCount[s2.major]++;
    majorCount[s3.major]++;
    majorCount[s4.major]++;
    majorCount[s5.major]++;

    for (const auto& pair : majorCount) {
        cout << "专业：" << pair.first << ", 人数：" << pair.second << endl;
    }

    return 0;
}